Thermostat.



THERMOSTAT.

stones.

Specification of Letters Patent.

Patented Nov. 15, 1910.

Application filed June 16, 1909, Serial No. 502.45%.

To all whom it may concern:

Be it known that Llticninn l-Ironllhxrrn, av citizen of the United States, and a reeldent of Denver, in the county of Denver and State of Colorado, have invented certain new and useful Improvements in Therniostatsoi' which the following is a specitication.

My invention relates to improvements in thermostats for closing electric circuits, and itconsists in the constructions, combinations and arrangements herein described and claimed.

An object ot' my invention is to provide a thermostat which may be used to close a circuit at a high tcn'iperaturc. as in case of a and thus sound an alarm or to-c'lose a circuit at a. predctcrmincd low temperature. in the latter case the device may be used to sound an alarm if crops are in danger of frost or to operate devices tor starting}; smudge tires.

A :t'urthcr object. of my invention is to provide a thermostat operated by the cr-cpansion and contraction of mercury in which the fluid is inclosed in a vessel from which it cannot. escape even it aporipcd and in which the movement of the contact maker is accomplished by means of a resilient tube which is stretched by the force oi the expanding fluid.

Other objects and advantages will appear in the followingspecification and the novel features of the device will be particularly pointed out in the appended claims.

lily invention is illustrated in the accompanying drawings in lwlilch Figure l is a vertical section through the device; Fig. 2 is a horizontal section along the linc2-2ofFig.1,a11d Fig.3 is a vcrtical section through a modified form oi. the device.

In carrying out. my invention 1 provide an outer tube or casing A, preferably of glass having a snuillcr concentric tube B disposed therein. The outer casing is closed at the upper end a, and the lower end 7) projects into the open end 0 of a receptacle (l arranged to contain mercury or other liquid. In the lower end of the tube A. is a centrally perforated partition I) through the opening of which the tube li extends. In the lower end of the tube B is a rubber thimble E which extends under the lower edge of the tube and is bent up so to lie between the tube and the partition D.

In the upper part of the tube B is the movable plunger; This comprises two hollow telescopic sections a and 6 containing a spiral spring c the upper section bearing the metallic contact head F which has the shape 01" av double cone and is designed to make connection between the upper terminals G and (r and between the lower terminals H and H. The lower receptacle C is made gas tight by a resilient ring K which fits in a groove at the top of the parts and bears against the tube or casing A.

From the foregoing description of the various parts of the device the operation thereof may be readily understood. The air from the upper part of the casing A is exhausted and the casing is sealed at L. The rubber thimble E and the receptacle G are tilled with mercury, the exact amount depending; upon the calibration of the device. When the device is heated the expansion oi. the mercury causes the resilient tube to stretch and to move the plunger 6 so as'to bring the head F into contact with the terminals G and G thereby completing a circuit tlirough them. When the temperature lowers the mercurv contracts and the contraction of the tube E allows the plunger to fall until the head contacts With the lower terminals H and H. The purpose of the telescopic sections 0 and c is to allow the head to engage the terminals G and G and in case the temperature should increase to permit the lower section to rise without moving; the upper.

In 3 I have shown av modified form.

In this term the plunger E is solid and has a rod M projecting from it which bears the bond F arranged to engage the two upper. contact springs S and fl and the lower terminals T and T in this form of the device the end of the rubber thimhle is between the main casing A and the partition 1?. in the preferred form and in the modification the upper tcri'ninals are in one electric circuit and the lower terminals are in another. The device may be made to sound an alarm by closing the circuit as in case of tire when the temperature rises or to sound an alarm when the temperature drops below a prcdctm'niincd point. the mercury in an air tight receptacle prevents the failure of the apparatus to Work on account. of the vaporization of the mercury when the temperature rises.

The inclosuro of I claim:

1. A thermostatcomprising a fluid receptacle a fluid in said receptacle, resilient, tube closed at its upper end and forming an extension of said receptacle. a rigid tube surrounding said resilient tube a plunger in said rigid tube adapted to be moved by said resilient extension, a contact head carried by said plunger, upper fixed contacts arranget'l to be engaged by said contact head when the resilient tube is extended through the expansion of the fluid and lower con tacis arranged to be engaged by the contact h aid when the resilient tube retracts from the contraction of the fluid.

2. In a thermostat a casing, a fluid receptacle secured to the lower part of said emcee casing, a rigid tube in said casting, a plan ger in said rigid tube, said plunger consist ing of telescopic inen'ibers, one of said lllt2ll1- hers bzaring a contact head, a resilient tube closed at one end and in communication with the fluid receptacle at the other end said resilient tube disposed in said rigid tube and arranged to engage the other ot said telescopic members, a spring normally forcing said telescopic members apart, upper and lower fixed contacts arranged to be engaged by said contact head. and an expansiblc fluid in said receptacle and said resilient; tube.

RICHARD HYDE i'ilklilll l. li itnessesz C. E. Hicnnrxo'ron, F. M. l-Ltn'ritrtocn. 

